Concrete mixer blade



March 14, 1933. A KNOW 1,901,305

CONCRETE MIXER BLADE Filed Dec. 28, 1929 F1G.4- D% 2 1 18.5. F'ZG. 6.

B-cr -21:

F7 a. 7 F1 6. 8. ('3 7L A A g 5 4 F15. 20.

E F F261. 9.

h I INVENTOR. x ALBERT KNawLEs. BY 1 Z'ITORNEYS.

Patented Mar. 14, 1933 ALBERT KNOWLES, or SAN rnANoIsco, cnriroam CONCRETE MIXER. BLADE Application filed December 28, 1929. Serial N 0. 417,109.

This invention relates to portable concrete mixers of the type shown in my copending patent application filed under Serial No. 406,359 and has for its object a special ar-.

rangement ofmi-xing blades for the revolvablemixing drum found after long experimentation to produce a more perfectmix with alarge load in a given length of time than formerly possible in a drum of the kind and in which the drum is of dimensions making it longer than its diameter.

In the drawing hereto annexed, Fig. 1 is a side view of a motor truck concrete mixer with a revolvable drum of the kind mentioned mounted thereon and backed up at an angle to receive its load of material through an opening the rear conical end of the drum. 7

Fig. 2 is an enlarged development plan of the drum with the drum cut'and unrolled flat to show the arrangement of mixing blades therein.

Figs. 3, 5, 7 and 9 are enlarged side elevations of the various blades used in the drum, whileFigs. 4, 6, 8 and 10 are respectlvely end elevations of the blades.

WVith respect to Fig. 1 the revolvable drum 1 mounted on motor truck 2, is closed at the front end, and provided with. a short conical end 3 at its rear end with around opening fitted with a removable doorwhichis locked in place over the opening during transportation-and mixing of the load, and removed for filling and discharging, ,orthe door is sometimes hinged. to the drum.

7 Transit mixing trucks of this kind are arranged for revolving of the drum in either direction by the truck engine and-to tilt the drum upwardly at its forward end to discharge the load by gravity from the conical end all by means of well known construction not shown. 7 I

As the cost of suchtruck mixers is very great. it has been found that they cannotbe 5 made to pay a proper return onv the investment unless the loadcarried is large relative to the cost of the mixer and accordingly attempts have'been made to utilize as long a drum as the truck would accommodate.

However, 'whenthis is done we run into the difficulty ofgetting an even mix from end to end of the drum, a difficulty long recognized and which is the reason why alllarge mixers of-the nonportable type are always short relative; to 7 their diameters, or so formed as by having the drum double-com icalinyshape'so as to constantly throw the material to'the center of the drum. a i

I-Ieretofore it has been customary to load the drums of truck or transit mixers about $9 half full, and sometimes less in order to secure a good mix, but as stated, thisat once reduced thereturns on the investment.

g In the present invention I am able to use a long drum, carry an extralarge-load, and yet'secure a perfect'mix from end to end of the drum in minimum length of time, f This is dueto the arrangement of blades within 7 the drumas well as the method of. loading to take advantage of the arrangement: of Y9 blades in building up a large load in the drum. .1 By my improvements there is provided a series (A, B, C) of bladeswithin the drum arranged atan angle to screw the'material' from the receiving or rear end toward the front end, other blades (D, E) tobodily lift the material, andanotherseries to screw the materialback towards the receiving end. i

In Fig. 2 the arrangement of theblades $9 on the development plan ofthe drum is shown, while Figs. 3 to 10 show the side and end views of the blades. o 7 'r-Blades B, C. and F are spaced outward from the wall of the drum to leave a. space j of about a couple of inches, while theother blades are in contact with the drumwall,

.Blade E is in a special position extending partly along the cylindrical wall of the drum and partly along the conical wall in :99 an angular manner as shown in Fig. 9; The function of this blade is to constantly throw some of the material outv of'the cylindrical portion into the conicaliportionof the drum, 7

lforzas it rises outof the material the or-- tion onthe cone assumes a downward s ant to, cause-the material to flow outwardlyfto thecone. More than one E blade may be used.

Thedrum is revolved in direction indicatbank it up as at 8, after which the wheel revolving the drum. WVhen discharging theload the drum is blocks 9 are moved forward a little, revolu tions of drum stopped, thevdoor or cover plate'lO clamped in place over the opening in the conical end of the drum, and the truck sent to itsdestination while again tilted and revolved in the opposite direc tion so that bladesA and B particularly will screw out or eject everybit of'material, the drum usually being rinsed out with alittle water before returning for the next load. r

' The invention is equally valuable whether used on ready mixed wet concrete material from a central plant, or upon'dry materials with water added just before leaving, or if used withwater-carryingmixers in which the water is added at the job or just before reaching'it. r

In considering Fig. 2 it will be seen that I provide two reverse series of blades C and F running the full length of the eye,

lindrical portion of the drum and that the individual blades of these series are in overlappingrelation." Also that the straight lifting blades D are scatteredthrough the drum in a manner so that the end of each is. overlapped at some point in the diameter of the drum by another D blade, and further that the extreme conical end of the A drum is fitted with screwing in or A blades 45 r only. a a

The value of blade or blades E would not be clearly seen by the layman, but it is of considerable importance in preventing segregation of the stones at the end of the load into the cone. j 7

Attention is also'called'to the fact that blade E as well as all of the other blades are transversely curved with concave side facing the direction of travel when mixing.

The general arrangement of blades described has been worked out after a long series of experiments for while at first thought it would seem that a mass of con crete materials revolved in a drum with blades lifting the material from beneath to fall on top would result in an even mix, practice has shown that this is not so 'as the constant motion will gradually separate the heavier stones from the other material, and

the difiiculty' of securing an even mix increases greatly with longer drums so that tests from Various parts of a mix made in prior long drum mixers showed a great difference in distribution of the cement and rock, so as to affect the strength all the way from 10 to 20% even after long mixing, whereas with my arrangement .of blades tests recently made in highway work showed a substantially even mix and strength from end to end of the drum, and since I have closely followed the development of the art and bu-iltmany such mixers I feel that the arrangement of blades in an elongated drum type mixer as disclosed represents an important advance in the art.

In thuspresenting my inventionI wish to say that I am fully aware of the fact that many patents have'been 'issuedflfor various arrangements of blades in aconcrete or other mixing drum, but most-of them-relate to the short type of drum only, and I am not aware that any successful arrangement of blades has heretofore been purposed which would operate successfully-with the long type of drum having one closed end and both receiving and discharging its load from-a single conical end, nor am I aware of any'system of loadinginwhich the directional action of the blades is made to (iooperate with the angular position of the truck and direction of rotation of the drum so as to build-up a large pay load as shown and described herein. r 1 I claim:' 7

1; In combination with a revolvable cylindrical concrete mixer drum which is relatively long to its diamete'rfa series; of angularly arranged; bIades'secured to the inner surface thereof extending substantially'fromend to end of the drum, and a similar series of opposite angular arrangement and a plurality of non-'angularly disposed lifting blades placed 3 at "various places throughout the drum in a manner to successively exert a lifting action on material from end to end of the cylinder.

2. In a construction as'specified in claim 1, the lifting blades being in contact with the side wall of the drum-and theang'u'larly arranged blades being spaced away there 3. In a revolvable cylindrical concrete mixer drum provided with a relatively short cone at one end through which'm'aterial to be mixed is received and discharged, a plurality of blades secured to the inner wall of the drum arranged at opposite angles of inclination forscr'ewing" the material back and forth in thecylindricalportion of the drum as thesameis revolved, and blades in the cone portion ofgthedrum inclined to screw the material one way only upon one way revolution of the drum. 1

I 4. In a revolvable cylindrical concrete 0 mixer drum provided witharel'atively short cone at one end through which material to be mixed is received and discharged, a lurality of blades secured to the inner wall of the drum, angularly disposed blades on the inside of the cone arranged to screw material from the cone into the cylindrical portion of the drum upon one way revolution of the drum and a blade extending from the cylindrical portion of the drum into the conearranged for leading materialfrom the cylindrical portion to said cone as the drum revolves.

ALBERT 

